Deleting lines from one file which are in another file

Question

I have a file f1:

line1
line2
line3
line4
..
..

I want to delete all the lines which are in another file f2:

Answer 1

Not a 'programming' answer but here's a quick and dirty solution: just go to http://www.listdiff.com/compare-2-lists-difference-tool.

Obviously won't work for huge files but it did the trick for me. A few notes:

• I'm not affiliated with the website in any way (if you still don't believe me, then you can just search for a different tool online; I used the search term "set difference list online")
• The linked website seems to make network calls on every list comparison, so don't feed it any sensitive data